In science a theory is best defined as a(n)
select one:
o a. educated opinion about the natural world.
o b. explanation for a large number of findings in the natural world.
c. personal understanding of natural laws.
d. testable prediction about the natural world.
o e. speculation and opinion of facts.

Firms use marginal analysis to determine prices by a) changing prices in accordance with information from retailers. b) using comparisons with strong competitors to position prices accordingly. c) examining the effect on revenue of small changes to the price of one item. d) trying to minimize production costs by using better and more efficient methods.